Method for producing stock material



Aug. 3, 1965 M. M. GRACER METHOD FOR PRODUCING STOCK MATERIAL 4 Sheets-Sheet 1 Original Filed July 9, 1959 INVENTOR WWI m Afar/4m? ATTORNEY 3, 1965 M. M. GRACER 3,197,860

METHOD FOR PRODUCING STOCK MATERIAL Original Filed July 9, 1959 4 Sheets-Sheet 2 INVENTOR" M/M/w /7 6mm ATTORNEY I Aug. 3, 1965 M. M. GRACER ,1

METHOD FOR rnonucme STOCK MATERIAL Original Filed July 9, 1959 4 Sheets-Sheet 4 BY WMMW ATTORNEY United States Patent 3,197,860 METHOD FOR PRODUCING STUCK MATERIAL Martin M. Gracer, 71 Laurel Drive, Massapequa Park, N.Y.

Application Mar. 8, 1962, Ser. No. 178,407, which is a division of application Ser. No. 825,954, July 9, 1959, now Patent No. 3,128,220, dated Apr. 17, 1964. Divlded and this application Oct. 29, 1964, Ser. No. 413,673 r 13 Claims. (Cl. 29-509) This application is a division of my application Serial No. 178,407, filed March 8, 1962, entitled Method and Feeder for Producing Stock Material, which in turn is a division of my application Serial No. 825,954, filed July 9, '1 959, now Patent No. 3,128,220, entitled Flexible Duct Connector Method of Making the Same and Resulting Product, which is a continuation-in-part of my application Serial No. 470,203, filed by me on November 22, 1954, now abandoned.

This invention relates to a method for making flexible connector stock. f

In my application aforesaid, I have provided a flexible duct connector stock for joining the ends of ducts to provide a flexible seal as between a blower or furnace and the duct leading therefrom in which two elongated lengths of sheet metal strips and a length of duct sealing fabric are joined in the composite so that each of said metal strips is joined-to the opposite side edges of the fabric. Specifically, in said application, the juncture between the fabric and the metal is formed by double folds, bending the metal into a flat tubular convolute of at least about one and one half turns, and double clinched in this condition by flattening the same during folding. Such composite of two strips of metal and a single web between them is then formed into a duct outline, either round or rectangular, to extend the opposite strips for juncture with permanent duct installations, to align the duct and a blower or furnace to accommodate for dimensional aberrations, to absorb objectional vibrations which might be transmitted through the length of the ducts. Stock for making such connectors is supplied to the market in extended lengths or coils of from fifty to one hundred feet, from which sections are cut off in the field for use. These coils are, in a measure, cumbersome to handle in that if coiled into a roll of too small a radius, the product will assume a permanent set when bent above the elastic limit of the composite and there then is involved the work of malleting, to take out the creases or waviness.

While other transverse bending stresses to which the composite above described is subjected, such as in the formation of duct outlines by inner and outer folds, do not relax the clinching between the metal and fabric by reason of the double fold in accordance with my prior application, a degree of inflexibility is experienced which involves unnecesary, high labor costs for handling.

I have found that in a connector in accordance with my present invention, I may beneficially retain a joint between the strips of metal and the composite edges of the duct sealing fabric employing a double fold in accordance with my prior invention whereby, in the extended condition of the metal strips in respect to the com mon fabric, abrasion of the fabric by the metal is avoided, securing other economies in package size of the stock and labor handling costs to form duct outlines transversely bent either at sharp angles or in gradual curves, employing heavy gauge sheet metal, by forming weakened areas along the folds in the composite where they are formed to clinch the metal to the fabric. Specifically, by providing transverse cutouts or scores, so that in retaining the benefits of a tubular convolute in clinching the metal to the fabric on its opposite edges, a more intimate engage- 3,197,860 Patented Aug. 3, 1965 ment may be elfected between metal and fabric by scoring the sheet which forms a portion of the convoluted edge, thereby securing, in the formation of a coil of the stock, a more compact and economical package.

Still more particularly, it is an object of my invention to provide a method of forming a flexible connector stock, which stock comprises uniformly shaped metal strips connected to opposite edges of a length of duct sealing fabric employing, at the metal strip side edges, a double fold, resulting in the formation of a tubular convolute of more than one turn, in clinched engagement with the fabric. The stock formed by this method may be handled in overlapped condition of the three components of metal and fabric economically and efiiciently, and be readily severed when required, with the same ease as a thinner stock.

Still more particularly, it is an object of my invention to provide a length of flexible connector stock composed of duct sealing fabric joined on its opposite edges by metal strips having double folds to clinch' the fabric and metal to each other, in which a warped condition is minimized, if not entirely eliminated, in which economy in space is effected, package sizes of long lengths are reduced, strong grip between fabric and metal is assured and accuracy in handling is enhanced.

A further object of the invention lies in providing a method of forming a length of connector stock of the type described, the resultant stock being susceptible of tight coiling to reduce package sizes without the tendency toward warping of the coiled stock.

Still more particularly, it is an object of this invention to provide a highly efficient method for forming connector stock, while effecting economies in production, storage and power forces in combining the layers of metal and fabric into clinching engagement to produce a double edge fold of metal to opposite sides of a duct sealing stock of fabric. To attain these objects and such further objects as may appear herein or be hereinafter pointed out, I make reference to the accompanying drawing, forming a part hereof, in which:

FIGURE 1 is a fragmentary perspective view showing the components entering into the stock in accordance with my invention;

FIGURE 2 is a sectional view showing an initial condition of juncture of the components shown in FIGURE 1;

FIGURE 3 is a sectional view showing the final condition of fold of the components shown in FIGURE 1;

FIGURE 4 is a plan view in the direction of the arrows 4-4 of FIGURE 3, with the parts overlapped ready for packaging;

FIGURE 5 is a fragmentary section taken on the lines 55 of FIGURE 4;

FIGURE 5a shows a coil of the product;

FIGURE 6 is a perspective view of the ultimate product, ready for bending transversely;

FIGURE 7 is a section taken on the lines 7-7 of FIGURE 6;

FIGURE 8 is a perspective View of an oblong form of duct made from the connector in accordance with my invention, with an inside fold of fabric;

FIGURE 9 illustrates a cylindrical form of duct in accordance with my invention, with an outside fold of fabric;

FIGURE 10 is a longitudinal diagrammatic side elevation of a means of forming the product in accordance with my invention;

FIGURE 10a is a fragmentary plan view ofthe positions of the strips when punched;

FIGURE 11 is a magnified fragmentary plan view of the aligning and metering components;

FIGURE 12 is a section taken on the lines 12-42 of FIGURE FIGURES 13 to 21 are side elevations, with work in section, showing the forming rolls in progressive steps in making the double edge fold of the composite in accordance with my invention.

Making reference to the drawing, a flexible connector stock in accordance with my invention is provided from a length of duct sealing fabric 10 and strips of sheet metal 11 and 12, different widths of such strips being employed, if desired.

The section It) may constitute duck impregnated to render the same impermeable to air or may be sections of woven asbestos fabric, also suitably treated to make the same relatively. impermeable to'the flow of gas therethrough, as well known in the air conditioning and heating and ventilating fields, and as described in my aforesaid application, by way of example.

The metal chosen is in accordance with that used in the heating and ventilating field for making ducts and may utilize galvanized sheet iron of at least 24 to 28 gauge thickness, though for small duct sizes a lesser thickness may be employed.

For purposes of illustration, the fabric 10 may be of an initial width of five. inches and of extended length of from fifty to one hundred feet. Strips 11 and 12 are each at least more than one half of the width of the fabric 10, and preferably one strip is of greater width than the other. For purposes of illustration, the strips may be four inches and five inches, respectively, and each is formed adjacent the side edges 13 and 14 with slotted cutout portions 15 of oblong outline, the length of which oblong is at least twice the overhang 16 between the outer edge walls 17 and 18 and the side edges 13 and 14, respectively. The width of the oblong is preferably, though not necessarily, large enough to provide clearance for the blade of a metal shipper. Where the slots 15 are made by a punching die, which is pre ferred, the burrs 15a are left to extend in the same facial direction for each strip 11 and 12, to provide a more intimate. fabric engagement when pressed into engagement with the same.

With lengths of strips 10, 11 and 12, so provided,-the leading edges 19, 2t and 21 of the three components are joined with the strips 11 and 12, overlapped at their edgesZ-Z, 23 for a distance to space the same so that the edges 17 and 18 are aligned with the side edges 24, 25 ofthe fabric 10. In this position, the edges 13 and 14 are given a first fold 26, 27, as shown in FIGURE 2, and then a second fold 28, 29, to form a tubular convolute of more than one turn, in the illustration providing a turn and a half of three layers ofv sheet metal and fabric except at the notched out portions 15.

Flattening the convolute to press the layers into intimate engagement at the folds will direct the burrs 15a previously described into greater frictional face engagement with the fabric. The width of the scoring with relation to the folded-in portion or overhang 16 extends diametrically across the convolute, to expose only two layers of sheet metal between the remnants of metal effected by the scoring 15. The spacing 31 defined by the scores 15 is of a nature to permit entry of the blade of hand snips to cut off or fashion the composite in the further procedure of converting a. length of stock into a duct, and thereby facilitate thistiresome operation.

When formed into short or indeterminate lengths of fifty to one hundred feet, with the metal layers overlapping'eachother and both under the overlying fabric as a. three layered component, the product may be packaged flat or in coils, as described in my prior application. Whenformed into coils, the differential thickness does not result in adverse warping or produce a permanent set by reason of the flexibility in forming the double folded edge with transverse scores or notches and packaged coils may be reduced in size. For instance, a coil of one hundred feet in length of 24 to 26 gauge metal, in accordance with my invention, may be packaged in a twenty-four inch square box, five to six inches deep, as compared with the necessity for using a thirty-six inch box for an unscored coil of similar length and gauge, in accordance with my prior application.

The space saving factor not only effects economies in storage and transportation but facilitates ease of handling due to the reduced bulk so that one individual may han dle a carton as compared with the necessity for handling of the larger size carton by two workmen. Coiling to the smaller dimension is possible without effecting waviness or distortion. A cut off length will quickly lie flat and may be readily worked and be bent to sharp corners on a bending brake, without rupturing the fabric, and in fact permitting the use of bending brakes to make corners of an angularity which normally would weaken the fabric.

When bent along the cross notches, the composite will furnish sharp cornered duct outlines without requiring an undue amount of malleting or bending dies to square up a corner. Forming inside folds (see FIGURE 8) or outside folds (see FIGURE 9) of the fabric in the formation of the duct of oblong outline O, or cylindrical outline C collars does not relax the clinched condition of the folds of metal and fabric in differential contraction due to the thickness of layers. Where the burrs 15a are formed by punching dies in making the notches l5, finishing operations to remove the burrs are unnecessary as the burrs enhance the grip between the fabric and condensing the enfolded fabric in clinching the folds.

The product aforementioned may be made in limited lengths or extended lengths and stacked fiat, one layer superimposed on another, or made in continuous lengths of from fifty to one hundred feet for handling, as decribed in my prior application, in coils. The employment of scored or notched blanks for making the composite has certain additional advantages and may be conveniently produced by procedure and apparatus which will now be described.

For this purpose, reference is made to FIGURES 10 to 21. In this assembly, raw stock for the strips 11 and 12 is supplied in the form of tightly wound coils A and B, respectively, of the metal, which are fed to a double punch 32 in side by side relationship, to punch the scores or sprockets 15 in an adjacent relationship to concentrate the punch power. i

A long, loose hanging flight 33- is provided beyond the punching zone which permits the strips 11 and 12 to be crossed over each other and reversed two ways from side by side position to another so that the scores or cutouts 15 are positioned remote from each other instead of being adjacent to each other as at the punching operation, and to position the lower faces so that they are upwardly directed. The burrs formed incident to the punching operation, which were downwardly disposed at the punch zone, thus are also upwardly faced. The strips are then overlapped, as shown in FIGURE 1, with relation to a width of duct sealing fabric and the leading edges fixedly secured together, as by riveting or spot Welding, so as to enter the hold down rollers 34 in a predetermined spaced apart, overlapped position, where the mated strips 11 and 12 are guided upon the platen 35, having side channel guides 3'6, 36a. The hold down rollers 34 optionally may, if desired, have interfitting sprockets for engaging the scores or cutouts 15, to coordinate movement of. the independent strips in unison without any relative differential movement. Suitable adjustable means (not shown) for urging the rollers into pressure engagement in accordance with the thickness of thecomposite of metal may be employed, as will be readily understood, and this arrangement is elfected for all of the journal boxes for the shafts of all of the guides or forming rolls in accordance with sound practice.

The side 13 of the strip 11 is thereby guided in abutting relation to the upstanding channel flange 36a and the side edge 14 of the strip 12 is abutted against the upstanding channel fiange 36. Thereupon the strip enters between opposed pairs of aligning mated rollers 37, 37a and 38, 38a, which grip the strips 11 and 12 through cutouts 39 in the platen 35, as shown in FIGURE 12.

The aligning mating rolls 37 and 38, and 37a and 38a, are of the same diameter and are preferably, although not necessarily, held on the common shafts. The rolls are free rolling on their common shafts 40 and 41. Ball bearing rollers (not shown) with inner and outer races are provided, the rolls rotating on theinner races. The shafts are fixedly mounted and do not rotate. The interengaging mating rolls 37 and 38, 37a and 38a are designed to maintain the edges 13 and 14 in diverging relation and in pressure contact with the upstanding channel guides 36:: and 36, respectively, beneath the hold down brackets 36b. This is effected by providing toe-in or leading edge camber to the rolls and by bending the shafts 40 and 41 a small angle, say 2 /z. The continuing outward pressure against the accurately parallel, upstanding channel of guides 36a and 36 thereby avoids any inaccuracy or variance in width of the strips 11 and 12, which overlap sufiiciently (the amount of overlap short of reaching the opposite edge being immaterial) and at the same time, by use of the series of forming rolls to be described, avoiding any guides whatever at an intermediate point, assure an accurate spaced relationship between the edges 13 and 14 of the strips in the further processing of the strips.

The strips 11 and 12 then proceed to engagement between pairs of metering mating rolls 42, 42a below and above the platen or bed 35. The metering rolls 42 and 42a are cylindrical and are truly square with relation to to the axial line of endwisely journalled upper and lower connecting shafts 43, to which the metering rolls 42 and 42a are keyed, to rotate the upper face rolls 42, 42a in unison and the lower face rolls 42 and 42a in unison. However, the shaft coupled rolls 42, 42a may be of differential diameter, depending upon whether the ultimate product is being packaged flat or in coil-s. Where the product is to be packaged in coils, I have devised means for assuring a length of the metal strips and fabric to be unwarped, when coiled and then uncoiled, by a reduction in the peripheral feed of the metering rolls 42a. This is accomplished by turning down the metering rolls 42a so that they have a peripheral length of one and one half inches less per one hundred feet than the metering rolls 42, with a 24 gauge stock of sheeting, as an example. Variations in coil characteristics, i.e., number of convolutions and lengths of stock with different thickness of metal and different thickness of fabrics, will require variations in the differential between the pairs of metering rolls and machine design to meet the changed con ditions, will acccordingly now be apparent.

The strips then pass between hold down plates 44, after which they are fed below the guide roll 45, whereby they meet the flight of duct sealing web of fabric fed thereto from the roller R over the guide rolls 46 to tauten the same.

The web of fabric 10 is centered with regard to the overlapping strips 11 and 12 so that the overhang 16, previously described, projects to each side edge of the fabric or selvage edge of the fabric, where a selvaged edge fabric is employed. For a five inch width fabric, the plates are positioned so that the edges 13 and 14 are spaced apart so that each gives an overhang of approximately five sixteenths of an inch, and press the fabric completely to cover the scores or cutout 15 and into engagement with the upstanding burrs 15a, and to compact the fabric for secure engagement. A three layered flat composite is then fed into the spaced-apart parallel series of mated upper and lower forming rolls, nine double groups being shown, where the double fold edges are impressed on the composite to form a flattened convolute of one and one half turns, pairs of upper and lower forming rolls 47, 47 and 47a, 47a impressing upon the edges 13 and 14, respectively, a 45 bend adjacent the weakened line of fold of the innermost wall of the cutouts 15, to engulf the edges 24 and 25 of the fabric 10. The provision of common, integrated shafts for the laterally spaced rolls and coupling for the mated forming rolls will be understood as desirable to assure uniformity,

and therefore have not been illustrated.

The web then passes through pairs of mated upper and lower forming rolls 48, 48 and 48a, 480, shown in FIG- URE 14, where the edges 13 and 14 are given a further 45 bend, to bring the same to Pairs of upper and lower mated forming rolls 49, 49 and 49a, 49a bend the overhang to as shown in FIGURE 15. Pairs of upper and lower mated fold rolls 50, 50 and 50a, 50a, as shown in FIGURE 16, form the overhang edge into the first fold 26, 27, and clinch the metal into engagement with the fabric. Thereupon the composite is fed to pairs of upper and lower mated rolls 51, 51, 51a, 51a, in which the first fold is bent 30, as shown in FIGURE 17. Thereupon the composite moves to pairs of upper and lower mated rolls 52, 52, 52a, 52a, where the first fold is given a further bend of 30, as shown in FIGURE 18. Thereupon, the composite moves to pairs of upper and lower mated rolls 53, 53, 53a, 53a, where the first fold is given an additional bend to 90, as shown in FIGURE 19. Thereupon the composite moves to pairs of upper and lower mated rolls 54, 54, 54a, 5411, where the first fold is bent to an angle of 135, FIGURE 20. Then the composite moves to pairs of upper and lower rolls 55, 55, 55a, 55a, where the first fold is bent FIGURE 21 to flatten and clinch the edges to the final convolute.

Each of the cooperating upper and lower rolls 47 to 55 which form the edge fold 29, maintains a differential peripheral length as compared with the series of rolls 47a to 55a, which form the double fold 28, to have the fold 29 of lesser peripheral length than the edge fold 28, thereby assuring a linear arrangement of the composite web at its side edges without any warping or camber or evidencing objectionable buckling when the finished product is coiled and uncoiled. As the length is fed into mating end guide rolls 56, 57 at the zone 58, periodic shearing may be effected by the shears 59 as the length is fed to a take-up creel where a core may be located, or a take-up linear chain carrier 60. Where a take-up carrier is employed, the composite may be stored flat in lengths of one hundred feet to be used from this source, or then wound into coils about a core which will provide an outer diameter of coil of twenty-four inches for such length, thereby permitting storage in a two foot square carton as compared with a three foot square carton for similar gauge metal and length of strip in previous packages. Such close coiling is made possible from flat stock or creeled stock at the station 60 without creating any permanent set in the composite when it is ready for use in the field, and has the advantages previously described as to flexibility, trueness of alignment and freedom from waviness.

The notched portions or scores provide weakened lines of fold, minimizing the stresses for making the folds and facilitating a spacing of the strips 11 and 12 to prevent differential stressing or crowding of the length of the composite occasioned by the overlapping and the multilayers which have been convoluted into the double folds. Benefits inure from the simultaneous folding operating of three composites in avoiding objectionable differential length or camber or warping as well as in permitting a creeling at the zone 60, with less tension components in making a coil of relatively small diameter. Yieldability by reason of the slotted or scored portions 15 permits tight coil creeling directly from the forming rolls or from stored continuous straight lengths of the composite, with the assurance that when the packaged coil is unrolled, lengths may be severed without waste.

I have not specifically shown the coupling of the shafts of the various mated feeding and forming rolls which have the ends of their supporting drive shafts extended and provided with suitable drive gears which are coupled to suitable driving means to assure powerized rotation in coordinated relation, to cause the composite stock to move in unison to the stock take-up means, such as a creel or a rectilinear extended chain carrier where continuous lengths of from fifty to one hundred feet or collected in the flat, preparatory to packaging in short lengths or in coils to provide a closely wound coil of about 24 inches in diameter, as described, for a one hundred foot length.

By my invention, substantial economies are effected in packaging, storage, handling, labor and working conditions, While producing a better quality product than described in my prior application.

While I have exemplified one form of my invention, it will be understood that modification will now readily become apparent and that the scope of my invention is to be broadly construed.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent is:

1. A method of making flexible connector stock comprising a pair of extended metal strips and a substantially coextensive length of duct sealing fabric web which consists in continuously feeding said metal strips in synchronism with the edge of one metal strip in substantial edge contact with one of the opposite side edges of the fabric web, with a weakened line of fold formed in the metal strip engaging portions of said fabric and continuously rolling a fold of each of said strips about each opposite edge of said fabric web by pressure rolling to clinch the metal strips and said fabric into engagemen with each other.

2. A method of making flexible connector stock in accordance with claim 1 wherein said weakened line of fold constitutes transverse scores.

3. A method of making flexible connector stock in accordance with claim 1 wherein said weakened line of fold constitutes transverse sections having projecting burrs.

4. A method of making flexible connector stock in accordance with claim 1 wherein said folding operation forms a convolute of more than one turn.

5. A method of making flexible connector stock in accordance with claim 1 wherein said score lines are transversely directed and extended for a width to provide weakened lines of fold at diametrically opposite portions of said convolute, thereby providing a cutoff gap of a reduced number of sheet metal thicknesses.

6. A method of making a flexible connector stock comprising an extended web of duct sealing fabric to each side edge of which there is connected a substantially coextensive metal strip which consists in continuously feeding said metal strips in synchronism, forming a weakened line of fold on adjacent edges to leave an overhang, spacing said edges from each other within a twisted flight of each strip, overlapping said strips while edgewisely directing said strips to maintain the same in a predetermined composite width, overlying a web of said fabric along the composite to extend over said weakened lines of fold and to leave said overhang of said metal strips to each side edge of said web of fabric uncovered, and simultaneously and continuously folding said overhang over said weakened line of fold into clinching engagement with the edge of said web to attach the edge portion of said metal strips to each of the side edges of said web of fabric.

7. A method of making flexible connector stock comprising an extended web of duct sealing fabric, to each side of which there is connected a substantially coextensive metal strip which consists in continuously and simultaneously feeding said metal strips along their length with a weakened line of fold comprising notches having inner and outer spaced walls, to leave a continuous overhang along the edges, overlapping said strips to position said weakened lines of fold on opposed side edges, overlying a web of said fabric along the composite to extend over said weakened lines of fold and to leave said overhang of said metal strips to each side edge of said web of fabric uncovered and simultaneously and continuously folding said overhangs substantially along a line over said outer walls of said notches to clinch the same into engagement with the corresponding edge of said web to attach the edge portion of said metal strips to each of said side edges of said web of fabric and form a first fold, and then folding the said first folded composite edge adjacent a line along the inner walls of said notches into clinching engagement to form a convolute of said composite, and flattening the same into clinching engagement.

8. In the method of making a flexible connector stock comprising an extended web of duct sealing fabric, to each side edge of which there is connected a substantially coextensive length of metal strip by continously feeding said strips in synchronism along a weakened line of fold, the steps which consist in first forming a weakened line of said strips in an adjacent position of edges of said strips to each other, and then directing flights of each of said strips in an unsupported hanging position while twisting each to space the edges with the weakened lines of fold in opposed position, and then continuously and simultaneously clinching said edges so formed into folded engagement with said web.

9. A method of producing a coil of a flexible connector stock comprising an extended web of duct sealing fabric, along each side of which there are connected substantially coextensive lengths of metal strips overlapping each other and overlapped by said fabric at the other side edge, said connection of said vmetal strips and fabric constituting a convolute of at least one turn, and said fold having weakened lines across the outer turn of said convolute, the steps which include coiling about a curve of a radius below the elastic limit of a lesser number of folded layers of said metal strips and above the elastic limit of the total number of folded layers of metal strips.

10. A method of producing a coil of a flexible connector stock comprising an extended web of duct sealing fabric, along each side of which there are connected substantially coextensive lengths of metal strips overlapping each other and overlapped by said fabric at the other side edge,-said connection of said metal strips and fabric constituting a convolute of more than one turn, and having weakened lines of fold across the outer turn of said convolute, the steps which include coiling about a curve of a radius below the elastic limit of two folded layers of metal strips and above the elastic limit of three folded layers of metal strips. I

11. A method of producing a coil of a flexible connector stock comprising an extended web of duct sealing fabric, along each side of which there are substantially coextensive lengths of metal strips overlapping each other and overlapped by said fabric at the other side edge, said connection of said metal strips and fabric constituting .a convolute of more than one turn, and having transverse notches in the portions diametrically across the outer turn of said convolute, the step of coiling about a curve of a radius below the elastic limit of two layers of metal strips and above the elastic limit of three layers of metal strips.

12. A method of producing a coil of a flexible connector stock comprising an extended web of duct sealing fabric, along each side of which there are connected substantially coextensive lengths of metal strips overlapping each other and overlapped by said fabric at the other side edge, said connection of said metal strips and fabric constituting a convolute of more than one turn and having transverse weakened lines of fold across the outer turn of said convolute, the step of coiling said composite about a curve of a radius which would produce a permanent set in the composite in the absence of the transverse weakened lines of fold.

13. The method of making a flexible connector stock comprising a pair of extended metal strips having weakened fold portions adjacent the edges thereof and a substantially eo-extensive length of duct sealing fabric web, which comprises continuously feeding said metal strips in synchronism, with the edge of one metal strip in substantial edge contact with one of the opposite side edges of the fabric web, with said weakened fold portions of said strip in engagement with said fabric, continuously rolling a fold of each of said strips by bending said strips in said weakened portions to fold said strip portions about the opposite edges of said fabric web, to elinchthe metal strips and said fabric into engagement with each other, each said clinched portion including at least three layers .15) of metal, and thereafter coiling the clinched composite about a curve of a radius below the elastic limit of a lesser number of folded layers of said metal strips and above the elastic limit of the total number of folded 5 layers of said strips.

References Cited by the Examiner UNITED STATES PATENTS 1,258,091 4/18 Clark 24278.3 1,727,184 9/29 Thompson.

2,395,878 4/ 46 Keene 29509 2,825,384 3/58 Goldsmith. 3,017,694 1/62 Goldsmith 29509 15 WHITMORE A. WILTZ, Primary Examiner.

CHARLIE T. MOON, Examiner. 

1. A METHOD OF MAKING FLEXIBLE CONNECTOR STOCK COMPRISING A PAIR OF EXTENDED METAL STRIPS AND A SUBSTANTIALLY COEXTENSIVE LENGTH OF DUCT SEALING FABRIC WEB WHICH CONSISTS IN CONTINUOUSLY FEEDING SAID METAL STRIPS IN SYNCHRONISM WITH THE EDGE OF ONE METAL STRIP IN SUBSTANTIAL EDGE CONTACT WITH ONE OF THE OPPOSITE SIDE EDGES OF THE FABRIC WEB, WITH A WEAKENED LINE OF FOLD FORMED IN THE METAL STRIP ENGAGING PORTIONS OF SAID FABRIC AND CONTINUIOUSLY ROLLING A FOLD OF EACH OF SAID STRIPS ABOUT EACH OPPOSITE EDGE OF SAID FABRIC WEB BY PRESSURE ROLLING TO CLINCH THE METAL STRIPS AND SAID FABRIC INTO ENGAGEMENT WITH EACH OTHER. 